Gyroscope system



May 30, 1944. f

A. M. 'FEDDE @Ynoscorjs SYSTEM original FiledfNov. 17, 194s v www-m may ffm ATTORNEYS Patented May 30, 1944 GYROSCOPE SYSTEM Arnold M. Fedde, Brooklyn, N. Y.,

Original application November 17, 1943, Serial No.

510,612. Divided and this application July 5, 1941, Serial No. 401,235

(Cl. 'lll-5) Claims.

This invention relates to gyroscope systems and more particularly to a system including two similar gyroscopes so constructed and arranged that relative angular displacement of the gyroscopes indicates with a high degree of accuracy the displacement of each gyroscope from its normal or neutral position.

In general, gyroscopes have been found to be extremely useful in many industrial and scientic applications because of the inherent tendency of a gyroscope to maintain a xed position in space. For some purposes gyroscopes are equipped with means for stabilizing the gyroscope axis in some desired position, for example a position parallel to the axis of the earth, or a vertical position. The familiar horizon gyroscope, for example, is equipped with mechanism for causing the gyrosccpe axis to return to a vertical position Whenever any extraneous force has caused the gyroscope axis to become inclined to the normal vertical position. Thus a horizon gyroscope, or gyro vertical, may be of the air blast controlled type in which small pendulums or pendulous vanes are employed to maintain the gyroscope erect. In this common type of gyroscope the pendulous vanes control air jets in such a way that the gyroscope axis is caused to seek a position parallel to the longitudinal axes of the vanes. Thus, when the force of gravity is the only substantial force acting on the vanes, the gyroscope axis is caused to seek and maintain a vertical position.

Any stabilizing mechanism employed for the purpose of causing a gyroscope to maintain a preferred position is of course affected by all forces acting on the system. For example, Where a gyro vertical is used on an airplane, acceleration forces other than the force of gravity act fon the control mechanism, and whenever there isA a change in the direction or magnitude'of the resultant force acting on the system there is a corresponding precession of the gyroscope whereby its axis of rotation seeks the direction of `this resultant force. In this way errors are introduced which may be of considerable magnitude, and, while such errors persist, the gyroscope axis does not give a true indication of the vertical. Heretofore, vario-us schemes have been devised with a view to curbing or eliminating the errors which would otherwise occur during the operation of a stabilized gyroscope, for, in most instances, reliance must be placed on the position ofthe gyroscope axis as an approximate indication of some selected position such as the true vertical or horizontal. The auxiliary devices heretofore employed for such purposes generally fail to give wholly reliable results.

In general, the principal object of my invention isto providey a gyrosccpe system including two gyroscopes, the system being of such a nature that it is not necessary to employ any auxiliary devices with a View to modifying or eliminating the errors which normally occur during the operation of any stabilized gyroscope employed in the system. This invention is based on a realization of the fact that a combination of two stabilized gyroscopes having the same kind of error law but of unequal sensitivity, provides an extremely accuratemeansfor determining the departure of either gyroscope from its neutral or normal position. Thus a preferred embodiment of my invention comprises two gyro verticals with means associated with the system wherebythe gyroscopes are of unequal sensitivity so that any change in the direction ormagnitude of the acceleration forces acting on the system causes relative angular displacement of the gyro axes'. Thus if the rate of precession of one gyroscope is twice that of the other gyroscope and at any given moment it is observed that the relative angular displacement of the two gyroscopes is 2 degrees, it is apparent that the axis lof the faster moving gyroscope is inclined at an angle of 4 degrees to the vertical and the axis of the slower moving gyroscope is inclined at an angle of 2 degrees to thevertical. For some applications it is not necessary to have the ratio of response 2 to l but in general I prefer to have the ratio of response at least 1.3 to 1 so that the relative angular displacement of the gyro axes will be appreciable and therefore readily determinable for the desired purpose. One gyroscope may be rendered more sensitive than the other by reduc.- ing the speedof rotation of the gyro rotor, by employing a rotor ofv less rotational mass (i. e. moment of inertia), by applying a greater erecting torque, or by employing a combination of these methods of increasing the sensitivity. It will be understood that the sensitivity of a gyroscope is its rate of precession or response to any change in the forces acting on the gyrosccpe andr that two gyroscopes may be said to have the same er.- ror law when their response to a change in the forces acting on them is similar except for the rate' of response.

As noted above, an object of this invention is to provide a gyroscope systemin-cluding two gyroscopes having the same error law but unequal sensitivity, and arranged so that the relative angular displacement vof the gyro axes provides an accurate indication of the displacement of either gyroscope from its normal or neutral position. A further object of this invention is to provide a specic application of such a gyroscope system whereby the errors of the separate gyroscopes are automatically cancelled for the practical purpose of providing an accurate indication of a selected position, 'for example the true vertical.

As an example of one embodiment of my invention, two gyroscopes of the horizon gyro, or gyro vertical type may have their gimbal rings mounted in a suitable support with the gyro axes of rotation in alignment or parallel 'to each other. One of the gyroscopes, which -may be called the pilot gyro, is twice as sensitive as the other gyro which may be termed the master gyro.

This difference in sensitivity is preferably at- 'y tained by utilizing in the pilot gyro a rotor having substantially one-half the rotational mass of the rotor vof the master gyro, or, if the rotors are of the same mass, thenth-e increased ksensitivitylma-y be obtained by applying 'greater erecting ,torque or reducing the speed of rotation of the pilotgyro rotor to a value equal to lsubstanjtiallyone-half the speed of rot'ationof the master gyro .rotor-.or any desired combination of these methods may be employed. The pilot gyro has associated therewith some convenient means for projecting van image in a direction parallel to or in alignment with the axis of Nthis gyroscope and the ,master gyro has associated with it a mirror having its surface avt-right angles to the axis of the master gyro, the `arrangement being such that the image is reflected by Athis mirror. A

conventional Vsighting system or telescope mechan'ism may be `associated with the .gyros in such ,a -way that the .reflected Vimage is visible therein. This system .is .such that theimage is reected from 'the mirror along a ,path that islsubstan tially vertical, regardless of the ,positions Vof the gyros with respect to eachother, or with respect .to the framesupporting the gyros. If the system .is used in an airplane, for example, the telescope mechanism may be such that the observer may see Vthe .reilected image and objects -below the the lfollowing detailed 1description of a specific embodiment of the invention illustrated in .the accompanying drawing, the single gure of which is a vertical section view, largely diagrammatic, of a gyroscope systemincluding sighting or telescope mechanism associated with the gyroscopes.

In the accompanying drawing the frame or support I carries a .pair of gyroscopes -2 and 3 hav'ingrotors rotating in the same direction and each 'having the usual gimbal .ring or Cardan mounting as shown at V4 and 5.

"The gyroscope 2, which may be termed a master gyro, Ycomprises a casing containing the :gyro rotor 6 and some means (such as .an air jet mechanism, not shown) for causing the gyro rotor to rotate at the desired speed. Each `gyroscope is provided with some means for causing the-gyro axesto seek 'the vertical. Such means are famillar to those skilled in this art and for the purpose of illustration 'I have shown pendulous `vanes controlling air ports lin the gyro casings.

Thus the master gyro 2 is equipped with four such varies in accordance with the usual practice, one of the varies being shown at 1, and the gyroscope 3, which may be characterized as a pilot gyro, is likewise equipped with four pendulous varies, one of which is illustrated at 8. The pendulous vanes on each gyro take positions in alignment with the resultant of acceleration forces acting on the system and cause the gyro to seek the direction of this resultant.

The pilot gyro 3 is more sensitive than the master gyro-2 or, in other words, the rate of response of the pilot gyro to forces tending to cause precession of the gyroscopes is greater than that of the master gyro `2. This difference in sensitivity )may vbe .attained in various ways, one of which is `to use in the tpilot gyro a rotor having less rotational mass than the rotor employed in the master gyro. For the purpose of illustrating this diagrammatically I have shown the rotor 9 of the pilot gyro as being of smaller dimensions than the rotor 6 of the master gyro and for the Vparticular system illustrated .in `the drawing the ployed the pilot gyro may be rendered twice as sensitive as the master .gyro by causing the pilot gyro rotor to rotate at substantially one-half the speed of rotation of the master gyro rotor. Furthermore, the gyros vmay Vbe .of such design and construction that the erecting torque of the pilot gyro is greater than that of .the `master gyro. My preferred method .of attaining `the desired difference in sensitivity however is .to employ in the pilot gyro a rotor having a smaller .rotational mass than that of the master gyro for Ain this way friction errors which Vmight be introduced where other `methods are employed, are avoided. In anyevent the gyro rotors rotatein the same direction vand both gyros may be Vsaid to have the same error law although they are of different sensitivity.

The-gyroscopesystem illustrated inthe accompanying drawing includes sighting mechanism and means for projecting an image which is invariably reflected along a vertical path regardless of .the relative angular position of the gyroscopes, thus providing a system admirably suited for yuse lon rairplanes and the like for accurate sighting purposes. To this end the pilot gyro 3 hasassociated therewith a source of light I0, a lreticle I I and a-collimating lens I 2-so 'arranged that the reticle image is projected in alignment with -or parallel -to the axis of rotation of the pilot gyro. For example, a sou-ree of light, reticle Aand lens may be carried by the pilot :gyro casing, or otherwise associated with the pilot gyro Lso thatthe projected beam `of light follows a path, the direction of which is always in alignment with or parallel to the axis of the pilot gyro. In like manner a mirror I3 is associated with the master gyro .in such .a way that its plane `is invariably at right angles to the axis of rotation of the master gyro rotor. This mirror I3 :may be mounted on the casing of the master gyro, or otherwise associated with it, so that its movements are lsynchronized with those of the master gyro.

'light source I0 and is inclined at an angle so :that the rays -of light reflected from the half diagrammatically shown as mounted in fixed relation with respect to the common'gyro-support and may include a system of reflecting* mirrors such as those shown at I6, I'I and I8 and suitable lenses such as those illustrated at I9 and 20, an

'eye-piece being shownvat El. A laminated light transmitting and reflecting element 22 may be mounted in the path of the reflected beam of light, this element being provided with a half silvered surface 23 and inclined at an angle so that objects at right angles to the beam of light transmitted to this element may be viewed through the sighting system.

To illustrate the operation of the specific embodiment of my invention illustrated in the accompanying drawing the sides of the support I are shown in a vertical position, and the pilot gyro 3 is shown with its axis inclined at an angle of 4 degrees to the vertical. The axis of the master gyro 2 is inclined'at an angle of 2 degrees to the vertical. The gyroscopes are thus in the positions they would occupy after a change in the resultant of the acceleration forces acting on the system had caused precession of the gyro axes away from their normal vertical positions. The vanes 1 and 8 are vertical, thus indicating that the force causing the precession of the gyros is no longer effective and thus the vanes are in a position to cause erection of the gyros to their' vertical position. Inasmuch as the master gyro 2 is inclined at an angle of 2 degrees to the vertical the mirror I3 is necessarily inclined at an" angle of 2 degrees to its normal horizontal position and the beam of light projected onto this mirror is reflected along a vertical path, because the angle of incidence is of course equal to the.

angle of reflection. The observer thus sees the image of the reticle reilected along a vertical path. If the system is mounted on an airplane the observer can sight objects on the ground in alignment with the image of the reticle and such objects are necessarily sighted along a vertical path. In this system the errors of the gyroscopes are automatically cancelled and the observer may sight along a vertical path regardless of the precession of the gyroscopes away from their normal vertical positions. If the airplane is inclined at an angle to the horizontal the support I will be inclined to the same extent and if the resultant acceleration force acting on the system has not caused precession of the gyroscopes their axes will be parallel to each other, both axes being vertical and the image reflected by the mirror I 3 will of course be reflected along a vertical path. If precession of the gyroscope occurs while the plane is thus inclined to the horizontal the amount of displacement of the pilot gyro from its vertical position will be twice the amount of displacement of the master gyro from its vertical position and the image will be reilected from the mirror I3 along the vertical path. Whenever it is noted that the gyro axes are inclined at an angle to each other this is an indication of the fact that extraneous forces have caused precession of the gyroscopes but, as noted above, in this sighting system the errors are in effect neutralized or canceled and the reiiected image invariably follows a path that is vertical, ignoring of course such errors as may be due to operation of the system at latitudes other than at the poles, and other gyroscope verrors familiar to those skilled in the art and which can be compensated for by Well known methods. In generaLmy irnproved system is such that relative angular displacement of the gyroscopes provides an accurate indication of the displacement of each gyroscope from its normal or neutral position. The gyroscopes may be of ordinary construction such for example as the familiar horizon gyro, with means for'rendering one of the gyros more sensitive or responsiveA than the other gyro and in the sighting system illustrated in the accompanying drawing the pilot gyro should be substantially twice as sensitive as the master gyro, thus insuring the reflection of the reticle image along a vertical path. l

It will be understood from the foregoing description that my invention contemplates the use of two stabilized gyroscopes of unequal sensitivity so arranged with respect to each other that they are each free to respond to any change in the forces acting on the system, whereby the relative displacement of the gyroscopes is commensurate with the displacement of either one of the gyroscopes. Such a device is capable of maintaining a fixed direction condition in the system. In the embodiment of the invention illustrated in the accompany drawing, for example, the sighting and image projecting mechanism associated with the gyroscopes indicates a true vertical position at all times regardless of the precession of the gyroscopes.

It is to be understood that my invention is not conned to the particular embodiments herein described in detail but includes such modifications thereof as fall within the scope of the appended claims.

I claim:

l. A gyroscope system comprising two gyroscopes, means for causing each of said gyroscopes to seek the direction of the resultant of acceleration forces acting on the system, means for rendering one of said gyroscopes more sensitive than the other gyroscope whereby any change in the forces acting on the system causes an indicatable relative angular displacement of the gyroscopes each of said gyroscopes being free to respond to any change in the forces acting on the system, and means for supporting said gyroscopes so that the relative displacement of the gyroscopes is commensurate with the displacement of one of said gyroscopes.

2. A gyroscope system comprising two gyroscopes. means for causing each of said gyroscopes to seek the direction of the resultant of acceleration forces acting on the system, means for rendering one of said gyroscopes substantially twice as sensitive as the other gyroscope whereby any change in the forces acting on the system causes an indicatable relative angular displacement of the gyroscopes, each of said gyroscopes being free to respond to any change in the forces acting on the system, and means for supporting said gyroscopes so that the relative displacement of said gyroscopes is commensurate with the displacement of said gyroscopes.

3. A gyroscope system comprising two gyroscopes having the same error law, means for rendering one of said gyroscopes more sensitive than the other gyroscope whereby any change in the forces acting on the system causes an indicatable relative angular displacement of the gyroscopes, each of said gyroscopes being free to respond to any change in the `forces acting on the system, and means for supporting said gyroscopes so that the relative displacement of saidgyroscopes is commensurate with the displacement of Aone of said gyroscopes.

4. A gyroscope system comprising two gyroscopes, a common support for said gyroscopes, means for causing each of said gyroscopes to seek the direction of the resultant of Yacceleration forces acting on the system, the rotational mass of the rotor of one of said gyroscopes being less than that of the other gyroscope whereby any change in the forces acting on the system vcauses an indicatable relative angular displacement of the gyroscopes, and means for mounting the two gyroscopes independently of each other on said support so that each gyroscope may respond freely to any change in the forces acting on the system.

5. A gyroscope system comprising two .stabilized gyroscopes of unequal sensitivity, a support and means for mounting the two gyroscopes on said support independently of each other so that each gyroscope may respond freely to any change in the forces acting on the system and any change in the forces acting on the system will cause an indicatable relative angular displacement of the gyroscopes.

ARNOLD M. FEDDE.

CERTIFICATE 0F CORRECTION. Patent No., 2,550,505. may 5o, 191m. ARNOLD M. FEDDE.

It is hereby certified that error appears in the above mnnbered patent requiring correction as follows: In le heading to the printed specificetion, lines Lg. and 5, strike out "Original application November 17, 1914.5 Serial No. 510,612. Divided and this application" and insert instead --Applicat'ion--g in the heading to the drawing, line 5, for "Original Filed Nov. 17, 19LL5 read --Filed July 5, 19Min; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

signed and sealed this 12th day of septenber, A. D. 191m.

Leslie Frazer (Seal) Acting commissioner of Patents. 

